Thermal module and manufacturing method thereof

ABSTRACT

A thermal module includes a substrate and a heat pipe integrally embedded in the substrate by insert molding technique. An end of the heat pipe protrudes laterally out of the substrate. The heat pipe includes a tube, a wick structure attached to an inner surface of the tube and a working fluid filled in the tube. A method for manufacturing the thermal module includes following steps: providing a tube with a wick structure attached to an inner surface thereof, an end of the tube being open; placing the tube into a mold; injecting a molten metal into the mold to form a substrate with the tube being integrally embedded in the substrate and the open end of the tube protruding laterally out of the substrate; filling a working fluid into the tube via the open end; sealing the open end of the tube.

BACKGROUND

1. Technical Field

The present disclosure relates to a thermal module and a manufacturing method of the thermal module.

2. Description of Related Art

With continuing development of electronic technology, heat-generating electronic components such as CPUs (central processing units) are generating more and more heat which requires immediate dissipation. Generally, thermal modules are attached to the electronic components to provide such dissipation.

A conventional thermal module includes a substrate, a fin assembly and a plurality of heat pipes connecting the fin assembly with the substrate. The substrate defines a plurality of elongated recesses for receiving the evaporator sections of the heat pipes. The evaporator sections of the heat pipes are respectively received in the recesses of the substrate and fixed to the substrate by soldering. Usually, a thermal interface material such as thermal grease is applied in the recesses to reduce air gaps between the heat pipes and the substrate. In manufacturing the thermal module, the substrate is defined with the recesses, and the heat pipes are assembled to the recesses of the substrate, which is time-consuming and complex. Furthermore, due to a technical restriction, the thermal grease can not be uniformly filled in a gap between the heat pipes and the substrate, which increases a heat resistance of the thermal module, and a heat dissipation capability of the thermal module is thus greatly reduced.

Therefore, a thermal module having a high heat dissipation capability and a simple manufacturing process is desired to overcome the above described shortcomings.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is an isometric view of a thermal module according to a first embodiment.

FIG. 2 is a cross-sectional view of the thermal module of FIG. 1, taken along a line II-II thereof.

FIG. 3 is a flow chart showing a method for manufacturing the thermal module of FIG. 1.

FIG. 4 shows a mold and plural tubes for forming the thermal module according to the method of FIG. 3.

FIG. 5 is a bottom plan view of a thermal module according to a second embodiment.

FIG. 6 is an isometric view of a thermal module according to a third embodiment.

DETAILED DESCRIPTION

Referring to FIGS. 1 and 2, the thermal module 100 includes a substrate 12 and a plurality heat pipes 16 integrally embedded in the substrate 12 by insert molding technique. The substrate 12 is made of metal such as aluminum which has a high heat conductivity coefficient. The substrate 12 is rectangular, including a planar bottom surface 122 adapted for contacting with a heat-generating electronic component (not shown) and a planar top surface 124 opposite to the bottom surface 122.

The heat pipes 16 have the same shape and structure. The heat pipes 16 each are elongated. Each of the heat pipes 16 includes a tube 162, a wick structure 164 received in the tube 162 and a working fluid (not shown) filled in the tube 162. The tube 162 is made of metal with high heat conductivity coefficient, such as copper. The tube 162 is hollow, defining a chamber 163 therein. The working fluid with a relatively low boiling point is filled in the chamber 163. The wick structure 164 is attached to an inner surface of the tube 162 surrounding the chamber 163. The wick structure 164 may be sintered powder, tiny grooves, or screen mesh. In this embodiment, the wick structure 164 is sintered powder. The wick structure 164 defines a plurality of pores therein which generate a capillary force to the working fluid.

The heat pipes 16 are parallel to and evenly spaced from each other in the substrate 12. Each of the heat pipes 16 extends from one lateral side of the substrate 12 to an opposite lateral side of the substrate 12 with two distal ends of each of the heat pipes 16 protruding laterally out of the substrate 12. The heat pipes 16 each are flat, and thus a planar contacting surface 161 is formed at a bottom side of each of the heat pipes 16. The contacting surfaces 161 of the heat pipes 16 are coplanar with the bottom surface 122 of the substrate 12.

Referring to FIGS. 3 and 4, in a method of manufacturing the thermal module 100, a plurality of hollow tubes 162 a each with a wick structure 164 a attached to an inner surface thereof are firstly provided, wherein one end of each of the tubes 162 a is open, and the other end of each of the tubes 162 a is sealed. A mold 18 is provided and the tubes 162 a are positioned in the mold 18. A molten metal is injected into the mold 18 to form the substrate 12 wherein the tubes 162 a are integrally embedded in the substrate 12 with two ends of each of the tubes 162 a protruding laterally out of the substrate 12. The tubes 162 a together with the substrate 12 are then taken out from the mold 18. Each of the tubes 162 a is vacuumed and a working fluid is filled into each of the tubes 162 a via the open end of each of the tubes 162 a, and then the open end of each of the tubes 162 a is sealed to form the heat pipes 16. Thus, the thermal module 100 with the heat pipes 16 integrally embedded in the substrate 12 is formed.

Before the tubes 162 a are positioned in the mold 18, the tubes 162 a each are flattened to form a contacting surface 161. The contacting surfaces 161 of the heat pipes 16 are coplanar to the bottom surface 122 of the substrate 12 such that the contacting surfaces 161 can contact the electronic component directly, to thereby absorb heat from the electronic component directly. The open ends of the tubes 162 a protrude laterally out of the substrate 12 such that the working fluid can be filled into the tubes 162 a via the open end of each of the tubes 162 a, and the open end of each of the tubes 162 a can be conveniently sealed.

As the heat pipes 16 are embedded in the substrate 12 by insert molding technique, the substrate 12 needs not to define recesses therein for receiving the heat pipes 16, and the heat pipes 16 need not to be assembled and soldered to the substrate 12, whereby the manufacturing process of the thermal module 100 is simple and convenient. In addition, the heat pipes 16 are integrally formed with the substrate 12 with no air gaps therebetween, whereby a heat resistance between the substrate 12 and the heat pipes 16 is greatly reduced; thus, a heat dissipation efficiency of the thermal module 100 is increased accordingly

During operation, the bottom surface 122 of the substrate 12 and the contacting surfaces 161 of the heat pipes 16 directly contact with the electronic component to absorb heat from the electronic component. The bottom surface 122 of the substrate 12 transfers the heat to the top surface 124 of the substrate 12, and then the top surface 124 of the substrate 12 radiates the heat to an outside environment or a fin assembly attached on the top surface 124. The contacting surfaces 161 of the heat pipes 16 absorb the heat and transfer the heat to the working fluid received in the chambers 163 of the heat pipes 16, and then the working fluid in the chambers 163 absorbs the heat and evaporates, the vapor carrying the heat moves to every area of the chambers 163 and releases the heat to the substrate 12. Thus, the heat is rapidly and uniformly spread to everywhere of the substrate 12. Since the heat pipes 16 are integrally connected with the substrate 12 by insert molding technique, the heat pipes 16 are intimately connected with the substrate 12 with no air gaps therebetween, such that the heat can be quickly transferred to the substrate 12, and a heat transfer capability of the thermal module 100 is thus increased accordingly.

FIG. 5 shows a thermal module 200 according to an alternative embodiment. The thermal module 200 is similar to the previous thermal module 100 of the first embodiment. The thermal module 200 includes a rectangular substrate 22 and plural heat pipes 26, 27. The thermal module 200 differs from the previous thermal module 100 in that the heat pipes 26, 27 of the thermal module 200 are different from the heat pipes 16 of the previous thermal module 100. In this embodiment, the heat pipes 26, 27 includes a first heat pipe 26 and two second heat pipes 27 which have a different shape from the first heat pipe 26. The first heat pipe 26 is linearly shaped, while the second heat pipes 27 each are bent to have a bow shape. The first heat pipe 26 is arranged centrally through the substrate 22. The second heat pipes 27 are located at two opposite lateral sides of the first heat pipe 26. Each of the second heat pipes 27 includes a linear portion 272 and two bent portions 271, 273 respectively extending slantwise from two ends of the linear portion 272 towards corners of the substrate 22. Ends of each of the first heat pipe 26 and the second heat pipes 27 protrude laterally out of the substrate 22. A method of manufacturing the thermal module 200 is the same as the method of manufacturing the previous thermal module 100 of the first embodiment.

FIG. 6 shows a thermal module 300 according to a third embodiment. The thermal module is similar to the previous first thermal module 100. The thermal module 300 includes a substrate 32 and a plurality of heat pipes 36. The substrate 32 forms a bottom surface 322 and a top surface 324 opposite to the bottom surface 322. The thermal module 300 differs from the first thermal module 100 in that a plurality of fins 34 are integrally formed on the top surface 324 of the substrate 32, and a shape of the heat pipes 36 is different from the heat pipes 16 of the first thermal module 100. The heat pipes 36 of the thermal module 300 each are U-shaped, including an evaporating section 362 and a condensing section 362 parallel to the evaporating section 362. The evaporating section 362 is integrally embedded in the substrate 32, while the condensing section 364 extends through and thermally connects with the fins 34. The evaporating section 362 of each of the heat pipes 36 forms a planar contacting surface 361 coplanar with the bottom surface 322 of the substrate 32.

A method of manufacturing the thermal module 300 is similar to the method of manufacturing the previous thermal module 100 of the first embodiment. When the thermal module 300 is manufactured, a plurality of tubes each with a wick structure attached to an inner surface thereof are firstly provided. Each of the tubes is flat in cross section and U-shaped in profile. Each tube includes a first section used for forming the evaporating section 362 of the heat pipe 36 and a second section used for forming the condensing section 364 of the heat pipe 36. One end of each of the tubes is open and the other end of each of the tubes is sealed. Secondly, the tubes are placed into a mold which is applied for forming the substrate 32 and the fins 34. Thirdly, a molten metal is injected into the mold to simultaneously form the substrate 32 and the fins 34 wherein the first sections of the tubes are integrally embedded in the substrate 32 and the second sections of the tubes integrally extend through the fins 34. Two ends of each of the tubes protrude laterally outside from the substrate 32. Then, a working fluid is filled into the tubes via the open ends of the tubes, and finally the open ends of the tubes are sealed, to thereby form the heat pipes 36 and the thermal module 300.

It is to be understood, however, that even though numerous characteristics and advantages of the disclosure have been set forth in the foregoing description, together with details of the structure and function of the embodiments, the disclosure is illustrative only, and changes may be made in detail, especially in matters of shape, size, and arrangement of parts within the principles of the invention to the full extent indicated by the broad general meaning of the terms in which the appended claims are expressed. 

1. A thermal module, comprising: a substrate; and a heat pipe being integrally embedded in the substrate by insert molding technique with at least one end of the heat pipe protruding laterally out of the substrate, the heat pipe comprising a hollow tube, a wick structure attached to an inner surface of the tube and a working fluid filled in the tube.
 2. The thermal module of claim 1, wherein the substrate forms a bottom surface adapted for contacting with an electronic component, and the heat pipe is flat and forms a planar contacting surface coplanar to the bottom surface of the substrate.
 3. The thermal module of claim 2, wherein the substrate further comprises a top surface opposite to the bottom surface, a plurality of fins integrally extending upwardly from the top surface of the substrate.
 4. The thermal module of claim 3, wherein the heat pipe is U-shaped, including an evaporating section integrally embedded in the substrate and a condensing section extending through the fins.
 5. The thermal module of claim 1, wherein the substrate is rectangular, the heat pipe extends centrally through the substrate, additional two heat pipes are provided at two opposite lateral sides of the heat pipe and integrally embedded in the substrate, the additional two heat pipes each includes a linear portion and two bent portions extending slantwise from two ends of the linear portion towards corners of the substrate.
 6. A method of manufacturing a thermal module, comprising: providing a hollow tube with a wick structure being attached to an inner surface of the tube, at least one end of the tube being open; providing a mold and positioning the tube in the mold; injecting a molten metal into the mold to form a substrate with the tube being integrally embedded in the substrate and the at least one open end of the tube protruding laterally out of the substrate; filling a working fluid into the tube via the at least one open end and sealing the at least one open end of the tube.
 7. The method of claim 6, wherein the substrate comprises a bottom surface and a top surface opposite to the bottom surface, a plurality of fins are integrally formed on the top surface of the substrate during the manufacturing of the substrate.
 8. The method of claim 7, wherein the heat pipe is U-shaped, including an evaporating section embedded in the substrate and a condensing section extending through the fins.
 9. The method of claim 6, wherein the substrate comprises a bottom surface, the heat pipe is flat and forms a planar contacting surface coplanar with the bottom surface of the substrate. 